Mushroom Growing Tips

SUBSTRATES: We mix recipes by hand or in a cement mixer for larger amounts. We generally allow soaking overnight.

BAGS: Unicorn bags type B filters allow for faster and more complete colonisation than A filters but are more prone to contamination, particularly for species which take longer to colonise such as shiitake.

BAG FILLING: Roll down the top of bag so you dont get sub on the tops. When filled, you can compress a bit but not too much.

AUTOCLAVING SUBSTRATE BAGS: We autoclave substrate bags for 2 hours at 121c and then cool under vacuum in the autoclave itself.

GRAIN SOAKING AND AUTOCLAVING: We put grains in water and boil for 20 minutes, however, we often also just put the grain in water for 24 hours to hydrate the seeds without boiling. Seeds should be drained well and allow to cool if the boiling step is carried out. Leave overnight for any thermotolerant spores to germinate. Autoclave for 4 hours – DO NOT overload the autoclave as air needs to get around the bags – 4 hours might be overkill but grain is very rich in nutrient, and can house many competing fungi and bacteria which if are not killed now, will cause problems later. Ideally, store the substrates in the refrigerator (2-4°C) and use them within 4 weeks. 

SPWANING FRUITING BAGS: For best results, add around 10% of the final weight of bags in grain spawn (e.g. 2,500g*0.2 = 250g of grain spawn). Higher percentages can be beneficial, but it can also be wasteful.

SPAWN RUN: Put bags at 25c with some fresh air exchange until fully white and firm. For shiitake, leave until the bags have gone dark brown.

ADD TO GROW ROOM: For shiitake, move bags into the grow room but dont open the bags until you see mushrooms start to form. We do this as shiitake are much more succeptible to contamination and so the less time they have ‘open’, the better your chances. Flip blocks over when moving to grow room – the extra moisture at the bottom of bags is more conducive to mushroom production. For oysters, we cut a two 3 inch slices (in a shape of an x) on the front and the top of the bags, then 2 major clusters are formed – however, our bags are large and for smaller bags and kits, one slice is good enough. For King oysters cut top off bag about 2 inches above the level of the substrate – you can add a damp vermiculite casing layer if you dont have ideal humidity conditions as this will help keep the conditions for fruting.

GROW ROOM CONDITIONS: 17-18c, plenty of fresh air exchange, >90 humidity.

Overall timings for our 5 mushrooms

Data taken from Paul Stamets’ book ‘Growing Gourmet Mushrooms’

All apparently require a cold snap, however, we have found this to be unnecessary – mushrooms can just be moved to the fruiting room/temp when ready.

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